A plant-monitoring control system is a system in which a programmable logic controller (PLC) which controls a plant and an input/output device are mutually connected via a network. The input/output device is an I/O connected to apparatuses (sensors and actuators) constituting the plant and a monitoring control device operated by an operator, which is a monitoring control device as a human machine interface (later HMI) with display items and operation items provided on a screen. PTL 1 discloses a data reproduction device connected to a network.
A conventional data reproduction device is designed as one communication apparatus on a network in advance at a design stage of a plant-monitoring control system. The programmable logic controller converts process data transmitted from the programmable logic controller to the input/output device and process data transmitted from the input/output device to the programmable logic controller to a dedicated data format which the conventional data reproduction device can understand. The programmable logic controller stores process data converted to the dedicated data format in a packet for which the data reproduction device is specified as a transmission destination address to transmit the packet. The conventional data reproduction device receives this packet and acquires the process data.
Thus, the dedicated data format is specified for the conventional data reproduction device, and it is necessary, even when process data is transmitted from the PLC or the input/output device by broadcast, for the PLC to convert the process data to the dedicated data format and separately transmit the process data to the data reproduction device.
Therefore, in the conventional data reproduction device, it is necessary to, in order to change process data to be acquired by the data reproduction device, change a communication program of the programmable logic controller that is operating to transmit the data to the data reproduction device, change settings for a network card (including an onboard one) that is operating and change settings for a monitoring control device (hereafter called HMI) and a data transmission process.